Mary Hudson

Long-term effects of non-linear frequency compression for children with moderate hearing loss

Abstract Objective: To evaluate non-linear frequency compression (NLFC) as a means to improve speech recognition for children with moderate to moderately-severe hearing loss following a six-month acclimatization period. Design: Within subject design with repeated measures across test conditions. Study Sample: Fifteen children, ages 5 to 13 years, with moderate to moderately-severe high-frequency sensorineural hearing loss were fitted with Phonak Nios, micro-sized, BTE hearing aids and evaluated after two six-week intervals with and without NLFC and again after a six-month period of consecutive NLFC use. Results: Using repeated measures analyses, the six-month results were compared to data that was collected following six-week trials with and without NLFC hearing aids (36). Improvements seen with NLFC in the initial study (36) were maintained or significantly increased in the present study. When compared to the six-week data, aided non-sense syllable speech recognition thresholds in quiet and speech recognition in noise were significantly better at the six-month interval. Conclusions: These results suggest that NLFC improves audibility for and recognition of high-frequency speech sounds for children with moderate to moderately-severe hearing loss. In many cases, improvements found with NLFC increased with a longer period of acclimatization to the technology. Sumario Objetivo: Evaluar la compresión no lineal de la frecuencia (NLFC) como un medio para mejorar el reconocimiento del lenguaje en niños con pérdidas auditivas moderadas a moderadamente severas, luego de un periodo de seis meses de aclimatación. Diseño: Es un diseño intra-sujeto con mediciones repetidas en todas las condiciones de la prueba Muestra del Estudio: Quince niños, edades de 5 a 13 años, con hipoacusia sensorineural moderada a moderadamente severa en altas frecuencias, fueron adaptados con auxiliares auditivos retroauriculares, de micro-tamaño, Phonak Nios, y evaluado luego de dos intervalos de seis semanas, con o sin NLFC y de nuevo, luego de un periodo de seis meses de uso consecutivo de NLFC. Resultados: Usando análisis de medidas repetidas, los resultados a seis meses se compararon con datos que fueron recogidos luego de periodos de seis semanas, con y sin auxiliares auditivos NLFC (Wolfe y col, en prensa). Las mejorías que se ven con NLFC en el estudio inicial (Wolfe y col, en prensa) se mantuvieron o fueron significativamente aumentadas en el presente estudio. Cuando se compararon con los datos de seis semanas, los umbrales no amplificados de reconocimiento del lenguaje para sílabas sin sentido en silencio y de reconocimiento del lenguaje en ruido, fueron significativamente mejores en el intervalo de seis meses. Conclusiones: Estos resultados sugieren que la NLFC mejora la audibilidad y el reconocimiento de sonidos lingüísticos de alta frecuencia para niños con hipoacusias moderadas a moderadamente severas. En muchos casos, la mejoría encontrada con NLFC aumentó con un periodo más largo de aclimatación a la tecnología.

The effect of front-end processing on cochlear implant performance of children.

Objective: Previous research shows that children using cochlear implants experience significant difficulty with speech perception in noisy listening situations. There are several types of input signal processing available for the cochlear implant sound processor; however, there is a paucity of research to support this technology for children. The primary objective of this study was to examine the potential benefits of 2 types of input signal processing, adaptive dynamic range optimization (ADRO) as compared with autosensitivity (ASC) plus ADRO for children using Cochlear Corporation implants. Research Design: Cross-sectional repeated-measures design. Setting: Outpatient nonprofit foundation providing audiology services and auditory-verbal therapy. Patients: Eleven children, aged 4 years 4 months to 12 years, with unilateral or bilateral Cochlear Limited implants. All children used their cochlear implant(s) for at least 1 year, had no additional disabilities, were enrolled in preschool or elementary school, and had age-appropriate receptive and expressive language. Intervention: All children used Cochlear Limited cochlear implants with either the Nucleus Freedom or Nucleus 5 cochlear implant sound processor. Performance was assessed while these children used ADRO-only input processing and ASC+ADRO input processing. Main Outcome Measures: Speech perception of PBK-50 monosyllabic words in quiet and BKB-SIN sentences in noise was measured for each child. In the noise conditions, children were using the ADRO-only or ASC+ADRO input signal processing strategies. The data in quiet were analyzed with descriptive statistics, and the conditions in noise were compared using a 1-way repeated-measures analysis of variance. Results: All children demonstrated word recognition in quiet at or above 90% correct. In noise, sentence-perception performance in the ASC+ADRO condition was significantly better than that in the ADRO-alone condition. Conclusion: The results of the study suggest substantial benefit from combining 2 types of input signal processing, ASC and ADRO, for children with unilateral and bilateral cochlear implants. Specifically, signal processing to adjust the sensitivity of the sound processor microphone automatically has substantial positive effects on speech-perception thresholds in noise.

Evaluation of wideband frequency responses and non-linear frequency compression for children with mild to moderate high-frequency hearing loss

Abstract Objective: To evaluate wideband amplification and non-linear frequency compression (NLFC) as a means to improve speech recognition for children with mild/moderate hearing loss. Design: Randomized within-subject design with repeated measures across test conditions. Study sample: Eleven children with mild to moderate hearing loss were evaluated with: (1) Phonak BTE without NLFC, (2) Phonak BTE with NLFC, and (3) Oticon BTE with wideband response extending to 8000 Hz. Results: Use of NLFC provided better detection and recognition of high-frequency stimuli (e.g. /sh/ and /s/). No difference in performance between conditions was observed for speech recognition when measured with the University of Western Ontario (UWO) plurals test and the UWO distinctive features difference test. Finally, there were no differences between conditions on the BKB-SIN test. Conclusions: Children with mild to moderate hearing loss have good access to high-frequency phonemes presented at fixed levels (e.g. 50 to 60 dBA) with both wideband and NLFC technology. Similarly, sentence recognition in noise was similar with wideband and NLFC. Adaptive test procedures that probe performance at lower input levels showed small but significant improvements in the detection and recognition of the phonemes /s/ and /sh/ with NLFC condition when compared to the NLFC Off and wideband conditions.

Evaluation of speech recognition of cochlear implant recipients using a personal digital adaptive radio frequency system.

BACKGROUND Previous research supports the use of frequency modulation (FM) systems for improving speech recognition in noise of individuals with cochlear implants (CIs). However, at this time, there is no published research on the potential speech recognition benefit of new digital adaptive wireless radio transmission systems. PURPOSE The goal of this study was to compare speech recognition in quiet and in noise of CI recipients while using traditional, fixed-gain analog FM systems, adaptive analog FM systems, and adaptive digital wireless radio frequency transmission systems. RESEARCH DESIGN A three-way repeated-measures design was used to examine performance differences among devices, among speech recognition conditions in quiet and in increasing levels of background noise, and between users of Advanced Bionics and Cochlear CIs. STUDY SAMPLE Seventeen users of Advanced Bionics Harmony CI sound processors and 20 users of Cochlear Nucleus 5 sound processors were included in the study. DATA COLLECTION AND ANALYSIS Participants were tested in a total of 32 speech-recognition-in noise-test conditions, which included one no-FM and three device conditions (fixed-gain FM, adaptive FM, and adaptive digital) at the following signal levels: 64 dBA speech (at the location of the participant) in quiet and 64 dBA speech with competing noise at 50, 55, 60, 65, 70, 75, and 80 dBA noise levels. RESULTS No significant differences were detected between the users of Advanced Bionics and Cochlear CIs. All of the radio frequency system conditions (i.e., fixed-gain FM, adaptive FM, and adaptive digital) outperformed the no-FM conditions in test situations with competing noise. Specifically, in conditions with 70, 75, and 80 dBA of competing noise, the adaptive digital system provided better performance than the fixed-gain and adaptive FM systems. The adaptive FM system did provide better performance than the fixed-gain FM system at 70 and 75 dBA of competing noise. At the lower noise levels of 50, 55, 60, and 65 dBA, no significant differences were detected across the three systems, and no significant differences were found across the quiet conditions. In all conditions, performance became poorer as the competing noise level increased. CONCLUSIONS In high levels of noise, the adaptive digital system provides superior performance when compared to adaptive analog FM and fixed-gain FM systems.

Effects of input processing and type of personal frequency modulation system on speech-recognition performance of adults with cochlear implants

Objectives: The objective of this study was to compare speech recognition in quiet and in noise for cochlear implant recipients using two different types of personal frequency modulation (FM) systems (directly coupled [direct auditory input] versus induction neckloop) with each of two sound processors (Cochlear Nucleus Freedom versus Cochlear Nucleus 5). Two different experiments were conducted within this study. In both these experiments, mixing of the FM signal within the Freedom processor was implemented via the same scheme used clinically for the Freedom sound processor. In Experiment 1, the aforementioned comparisons were conducted with the Nucleus 5 programmed so that the microphone and FM signals were mixed and then the mixed signals were subjected to autosensitivity control (ASC). In Experiment 2, comparisons between the two FM systems and processors were conducted again with the Nucleus 5 programmed to provide a more complex multistage implementation of ASC during the preprocessing stage. Design: This study was a within-subject, repeated-measures design. Subjects were recruited from the patient population at the Hearts for Hearing Foundation in Oklahoma City, OK. Fifteen subjects participated in Experiment 1, and 16 subjects participated in Experiment 2. Subjects were adults who had used either unilateral or bilateral cochlear implants for at least 1 year. Results: In this experiment, no differences were found in speech recognition in quiet obtained with the two different FM systems or the various sound-processor conditions. With each sound processor, speech recognition in noise was better with the directly coupled direct auditory input system relative to the neckloop system. The multistage ASC processing of the Nucleus 5 sound processor provided better performance than the single-stage approach for the Nucleus 5 and the Nucleus Freedom sound processor. Conclusions: Speech recognition in noise is substantially affected by the type of sound processor, FM system, and implementation of ASC used by a Cochlear implant recipient.

Evaluation of Performance With an Adaptive Digital Remote Microphone System and a Digital Remote Microphone Audio-Streaming Accessory System

PURPOSE One purpose of this study was to evaluate the improvement in speech recognition obtained with use of 2 different remote microphone technologies. Another purpose of this study was to determine whether a battery of audiometric measures could predict benefit from use of these technologies. METHOD Sentence recognition was evaluated while 17 adults used each of 2 different hearing aids. Performance was evaluated with and without 2 different remote microphone systems. A variety of audiologic measures were administered to determine whether prefitting assessment may predict benefit from remote microphone technology. RESULTS Use of both remote microphone systems resulted in improvement in speech recognition in quiet and in noise. There were no differences in performance obtained with the 2 different remote microphone technologies in quiet and at low competing noise levels, but use of the digital adaptive remote microphone system provided better speech recognition in the presence of moderate- to high-level noise. The Listening in Spatialized Noise–Sentence Test Prescribed Gain Amplifier (Cameron & Dillon, 2010) measure served as a good predictor of benefit from remote microphone technology. CONCLUSIONS Each remote microphone system improved sentence recognition in noise, but greater improvement was obtained with the digital adaptive system. The Listening in Spatialized Noise–Sentence Test Prescribed Gain Amplifier may serve as a good indicator of benefit from remote microphone technology.

Evaluation of wideband frequency responses and nonlinear frequency compression for children with cookie-bite audiometric configurations.

BACKGROUND Previous research has suggested that use of nonlinear frequency compression (NLFC) can improve audibility for high-frequency sounds and speech recognition of children with moderate to profound high-frequency hearing loss. Furthermore, previous studies have generally found no detriment associated with the use of NLFC. However, there have been no published studies examining the effect of NLFC on the performance of children with cookie-bite audiometric configurations. For this configuration of hearing loss, frequency-lowering processing will likely move high-frequency sounds to a lower frequency range at which a greater degree of hearing loss exists. PURPOSE The purpose of this study was to evaluate and compare the effects of wideband amplification and NLFC on high-frequency audibility and speech recognition of children with cookie-bite audiometric configurations. RESEARCH DESIGN This study consisted of a within-participant design with repeated measures across test conditions. STUDY SAMPLE Seven children, ages 6-13 yr, with cookie-bite audiometric configurations and normal hearing or mild hearing loss at 6000 and 8000 Hz, were recruited. INTERVENTION Participants were fitted with Phonak Nios S H2O III behind-the-ear hearing aids and Oticon Safari 300 behind-the-ear hearing aids. DATA COLLECTION The participants were evaluated after three 4-to 6-wk intervals: (1) Phonak Nios S H2O III without NLFC, (2) Phonak Nios S H2O III with NLFC, and (3) Oticon Safari 300 with wideband frequency response extending to 8000 Hz. The order in which each technology was used was counterbalanced across participants. High-frequency audibility was evaluated by assessing aided thresholds (dB SPL) for warble tones and the high-frequency phonemes /sh/ and /s/. Speech recognition in quiet was measured with the University of Western Ontario (UWO) Plurals Test, the UWO Distinctive Features Difference (DFD) Test, and the Phoneme Perception Test vowel-consonant-vowel nonsense syllable test. Sentence recognition in noise was evaluated with the Bamford-Kowal-Bench Speech-In-Noise (BKB-SIN) Test. ANALYSIS Repeated-measures analyses of variance were used to analyze the data collected in this study. The results across the three different conditions were compared. RESULTS No difference in performance across conditions was observed for detection of high-frequency warble tones and the speech sounds /sh/ and /s/. No significant difference was seen across conditions for speech recognition in quiet when measured with the UWO Plurals Test, the UWO-DFD Test, and the Phoneme Perception Test vowel-consonant-vowel nonsense syllable test. Finally, there were also no differences across conditions on the BKB-SIN Test. CONCLUSIONS These results suggest that NLFC does not degrade or improve audibility for and recognition of high-frequency speech sounds as well as sentence recognition in noise when compared with wideband amplification for children with cookie-bite audiometric configurations.

Better Speech Recognition with Digital RF System in Study of Cochlear Implants

Hearing aid wearers often have difficulty understanding speech in the presence of background noise and reverberation (J Acous Soc Am 2008;124[5]:3064-3075; J Acoust Soc Am 1978;63[2]:533-549). They also may run into trouble when the signal of interest originates from across a large room. Remote microphone hearing assistive technology (HAT), more commonly referred to as a personal frequency modulation (FM) system, generally is the most effective method to improve performance in such challenging listening situations (J Speech Hear Disord 1984;49[4]:409-418; J Speech Hear Disord 1984;49[3]:278-286 ; Am J Audiol 2010;19[1]:36-45). These systems capture the signal of interest near its source, leading to a much more favorable signal-to-noise ratio (SNR) compared with that at the microphone of the hearing aid. Taking this information into account, we compared different types of hearing assistive technology to see if one approach was better than another in these difficult listening environments. We found that cochlear implant recipients using a digital radio frequency (RF) system had better speech recognition, especially at high noise levels, than those using other technologies.

Evaluation of the benefits of binaural hearing on the telephone for children with hearing loss.

BACKGROUND There is a paucity of published studies examining how children with hearing loss understand speech over the telephone. Previous studies on adults with hearing aids have suggested that adults with bilateral hearing aids experience significant difficulty recognizing speech on the telephone when listening with one ear, but the provision of telephone input to both ears substantially improved speech understanding. PURPOSE The objectives of this study were to measure speech recognition in quiet and in noise for a group of older children with hearing loss over the telephone and to evaluate the effects of binaural hearing (e.g., DuoPhone) on speech recognition over the telephone. RESEARCH DESIGN A cross-sectional, repeated-measures design was used in this study. STUDY SAMPLE A total of 14 children, ages 6-14 yr, participated in the study. Participants were obtained using convenience sampling from a nonprofit clinic population. INTERVENTION Speech recognition in quiet and in noise with binaural versus monaural telephone input was compared in pediatric participants. DATA COLLECTION AND ANALYSIS Monosyllabic word recognition was assessed in quiet and classroom noise set at 50 dBA in conditions with monaural and binaural (DuoPhone) telephone input. RESULTS The childrens speech recognition in quiet and in noise was significantly better with binaural telephone input relative to monaural telephone input. CONCLUSIONS To obtain optimal performance on the telephone, the following considerations may apply: (1) use of amplification with binaural streaming capabilities (e.g., DuoPhone), (2) counseling of family and children on how to best use the telephone, (3) provision of telecoil with microphone attenuation for improved signal-to-noise ratio, and (4) use of probe tube measures to verify the appropriateness of the telephone programs.

Evaluation of noise reduction technologies in a contemporary cochlear implant system

Advances in cochlear implant technology have resulted in excellent outcomes for most pediatric and adult recipients. Specifically, most adult cochlear implant users can converse over the telephone and perform at ceiling levels (i.e., 100%) on open-set sentence recognition tests used for clinical assessment,1-4 while many children who receive a cochlear implant at an early age develop age-appropriate speech, language, and academic abilities.5-7 Despite these advances, many cochlear implant users continue to experience substantial difficulty with speech recognition in noisy environments. In particular, recent studies have shown that speech understanding decreases by 30 to 60 percentage points when performance in quiet is compared with performance at commonlyencountered signal-to-noise ratios ranging from +4 and +10 dB.8-11 As a result, cochlear implant manufacturers invest considerable resources into the development of technologies designed to improve speech perception in noise. For example, the newly-introduced Cochlear Nucleus 5 cochlear implant system possesses several features that are intended to improve speech understanding in noisy environments, which include: Preprocessing strategies designed to augment the speech signal while reducing the salience of the background noise; Microphone technology intended to improve the signal-to-noise ratio to the listener; and Simple and improved connectivity of the implant processor to personal FM systems. The following three sections provide an overview and evidence to support the use of the aforementioned features through discussions of preliminary experiences from studies conducted with children and adults using the Nucleus 5 cochlear implant system.